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The dream of materials design is to leverage our theories of electronic structure, rather than ignoring them, and combine it with our increasing computational ability to discover new materials. Beyond its technological implications, the challenge of materials design is also one of great intellectual depth. In principle, we know the fundamental equation needed to model the behavior of a material: it is the Schr\"odinger equation, describing electrons moving in the potential of a periodic lattice, mutually interacting via the Coulomb repulsion. Solving this equation is another matter.  In a sense, we distinguish classes of materials by how well we can solve its corresponding Schr\"odinger equation. For weakly-correlated materials, we have a well-developed theory of their excitation spectra, namely Fermi liquid theory, and practical tools for modeling their properties.  These materials encompass simple metals, insulators and semiconductors, implementations of density functional theory (DFT) performs extremely well. DFT is a workhorse of the materials science community, providing efficient and accurate computations of the total energy and distribution of electrons of a compound, requiring only the coordinates of the atoms in its crystal lattice as input. From the total energy, one can obtain lattice constants, equations of state and the spectrum of lattice vibrations. Furthermore, one can obtain electronic properties such as band gaps, electric polarization and topological numbers, which are by no means trivial for these "simple" compounds.  Frontier: intersection of correlated theory and materials design.  and we distinguish to classes of materials in this respect. For weakly correlated electron materials, we have a well develop theory of the excitation spectra, the Fermi liquid theory, and practical tools for their computation. %  and most recently, hydrogen sulfide in late 2014--have been discovered by chance.For weakly-correlated compounds, encompassing simple metals, insulators and semiconductors, implementations of density functional theory (DFT) performs extremely well. DFT is a workhorse of the materials science community, providing efficient and accurate computations of the total energy and distribution of electrons of a compound, requiring only the coordinates of the atoms in its crystal lattice as input. From the total energy, one can obtain lattice constants, equations of state and the spectrum of lattice vibrations. Furthermore, one can obtain electronic properties such as band gaps, electric polarization and topological numbers, which are by no means trivial for these "simple" compounds.  It starts with  the Kohn-Sham formulation~\cite{Kohn_1965} of density functional theory.